文档介绍：Oscillator Phase Noise Reduction
Using Nonlinear Design Techniques
by
David S. M. Steinbach
Thesis submitted to the Faculty of the
Virginia Polytechnic Institute and State University
in partial fulfillment of the requirements for the degree of
MASTER OF SCIENCE
in
Electrical Engineering
Dr. W. A. Davis, Chairman
Dr. C. W. Bostian
Dr. D. G. Sweeney
8 May 2001
Blacksburg, Virginia
Key Words: Design, Nonlinear, Oscillator, Phase noise,
Copyright 2001, David S. M. Steinbach
Oscillator Phase Noise Reduction
Using Nonlinear Design Techniques
David S. M. Steinbach
(ABSTRACT)
Phase noise from radio frequency (RF) oscillators is one of the major limiting factors
munication system performance. Phase noise directly effects short-term
frequency stability, Bit-Error-Rate (BER), and phase-locked loop adjacent-channel
interference.
RF oscillator circuits contain at least one active device, usually a transistor. The active
device has noise properties which generally dominate the noise characteristic limits of an
oscillator. Since all noise sources, except thermal noise, are generally proportional to
average current flow through the active device, it is logical that reducing the current flow
through the device will lead to lower noise levels. A theory based on the time-varying
properties of oscillators proposes that narrowing the current pulse width in the active
device will decrease the time that noise is present in the circuit and therefore, decrease
phase noise even further.
The time-domain waveforms and phase noise of an active-biased 700MHz oscillator
are analyzed, showing heavy saturation and high-harmonic content. Redesigns of the
example oscillator in active-bias and four-resistor-bias configurations show improved
phase noise and lower harmonic levels at the output. Five oscillator designs of each bias
configuration, each having a different pulse width, are simulated. As predicted by the
theory, the narrowest current p